Anyone ever swapped out the gas tank on 82 750K?

I just recently bought my first bike; 1982 cb750K. I don't know much about bikes and it hurts to say that. I've worked as a composite fabricator and an aircraft mechanic for 9 years professionally and i worked on cars extensively for 10 years prior (im 31).

Over the course of the past two weeks, I've done what i always do and obsessively read, watch, and listen to everything that i can, to teach myself as much as possible.
That being said, I've looked all over and still haven't found any substantial write ups or anyone who's swapped out the square ass gas tank that comes on these bikes.
I'm planning on doing a low to the ground brat style build. Primary intention and purpose is to have something to ride to work and ride around town (I live in Denver CO).
I'll get around to posting photos once i get some time to get the bike out in the sun and have good light.
Its only got 7000 original miles on it and the previous owner did his version of a cafe racer to it. I'll be removing most of it and building this bike to match my vision.

I hate the 1981-1982 gas tanks.
I'd like to put a mid 70s 750 tank on it.

Also, this is my first thread post.

Try a ‘79 to ‘83 C model tank.
I’ve had and ridddin all 3, F, K and C.

The C model tank is by far the most comfortable tank of the 3.

I didn't like my k tank at first but it grew on me. I still like the c tank, too, as it carries that timeless cafe racer feel

brettp said:

I didn't like my k tank at first but it grew on me. I still like the c tank, too, as it carries that timeless cafe racer feel

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It's funny you say that. As I was removing everything to take accurate measurements for my seat, I kept catching myself standing back and thinking "damn... that tank really doesn't look BAD".

The K tank is a sportier tank, IMHO. I think your bike looks great!

If you don't like that 81-82 F tank, let me know if you want to sell it!?

His bike does look good.

brettp said:

The K tank is a sportier tank, IMHO. I think your bike looks great

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The question I’m asking…is what are you gonna do for a seat?
I have an 82 in storage, all OEM, and it’s the K seat that I’m not really fond of.

If you’re goin brat, what’s you’re thoughts on a seat?

Motogrady said:

The question I’m asking…is what are you gonna do for a seat?
I have an 82 in storage, all OEM, and it’s the K seat that I’m not really fond of.

If you’re goin brat, what’s you’re thoughts on a seat?

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Well, I've been thinking about it quite a bit and I think I've settled on buying the brat style seat from TUFFSIDE. I fancy the distressed brown material with the saddle color stitching and will be getting a matching grip set. However, I will admit, I'm beginning to feel a bit overwhelmed with ALL of the information I'm trying to take in. That being said, I'm a bit confused as to what an entire seat setup consists of. I've seen a few videos on YouTube of guys making their own seat pans out of fiberglass, which I think is pretty cool. I have a massive roll of carbon fiber that was "not fit for spaceflight" from one of my previous jobs, and figured if I want to go that route, I could lay up over packing tape and trim accordingly once it's set. But it also seems like the only reason I'd need to make my own seat pan is so that I could build the seat on it. If I buy a pre-made 750 seat from that guy at Tuffside, it's my understanding that that's what he's already doing. From bottom to top its: seat pan, foam, upholstery and stitching. If someone could clarify that for me, that'd be great. I've also seen people lay up their seat pan and then send it to him to foam and upholster and finish, but I assume this is for more of a exact fit for their bike. Again, if someone could shed some light on that. I've got some pretty crippling ADD and when I obsess over projects like this, it's hard for me to see a stream of research all the way through and I jump around a lot as different questions pop into my head. I usually get to where I need to with my research but it can take a while with my "look! Squirrel!" thinking.

Something else to add that relates to the tank, the seat I'm looking at is always shown on 750s without the F tank, and it has a slight upturn towards the front of it where it meets the tank. I don't particularly like the look of the upturn and would prefer to have the foam shaped to maintain the straight line that runs horizontal and parallel with the frame of the bike. I'll include some photos that I've downloaded from their website as well as a few that I've marked up showing that straight line that I'd like. There HAS to be a photo of someone with the tuffside seat on a bike with the same tank as mine but I've yet to find it. Might just need to take a lunch break at work and spend 45 minutes doing nothing but trying to find it.

Another thing I've made an observation of, is that once the seat is installed, it's obvious that there's nothing under it to protect it from all the shit that'll fly up from the rear tire. I've seen a few photos where people are welding a plate under the newly installed hoop, that connects to their custom fabbed electronics shelf/ bay/ box. It seems like there could be several options of how to remedy that situation. Anyways... As always, I'm looking forward to your input and opinions.

Bo82CB said:

If you don't like that 81-82 F tank, let me know if you want to sell it!?

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I was under the understanding that I've got a "K" tank. Can you explain more?

Motogrady said:

Try a ‘79 to ‘83 C model tank.
I’ve had and ridddin all 3, F, K and C.

The C model tank is by far the most comfortable tank of the 3.

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Is the C tank a direct bolt on replacement? I really like the shape of it. As far as comfortability, what sort of setup do you have with those tanks? Rearsets? Aftermarket handle bars? I'm a bit embarrassed to admit that I just installed some clip on handlebars to bring the handles back towards me some more, but the quality of them and the amount of unmeasured torque that I've had to put on both the x and y axis seems like an unhealthy amount. Not to mention, I'm struggling to understand how to symmetrically align them. I'm 5'4" and reaching all the way up to where the previously installed grips were was super uncomfortable.

Look at the back end of your tank, it is upside down U shaped, that's the reason for the uplift at the front of the seat.

mrtwowheel said:

Look at the back end of your tank, it is upside down U shaped, that's the reason for the uplift at the front of the seat.

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Correct. I don't like that. I'd rather the seat be flat and not following the conture of the tank. As in, I'd rather there be a gap.

This?

That green tank sure looks like an F tank.

Single disc up front.
Drum in rear.
That’s a K or a C
But, spoke wheels who knows.

Both supposed to be 82s

Motogrady said:

This?

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That EXACTLY. At first I didn't notice the black paint masking the downturn shape of the tank, but yeah man, that seat is PERFECT.

jasonscb750build said:

That EXACTLY. At first I didn't notice the black paint masking the downturn shape of the tank, but yeah man, that seat is PERFECT.

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Do you know who made that seat?